Metering system



T. .17 fi J 7 m i lNVENTOR JOHN H. LEVIS m2.

ATTORNEY J. H. LEVIS. JR

METERING SYSTEM Aug. 23, 1932.

Filed Sept- 1925 1 preventing Patented Aug. 23, 1932 UNITED stares PATENT OFFICE JOHN H. LEVIS, JR, ornocnnsrnn, new-$203K; AssIGNon TO THE s'rRoMBnne-cAaL- SON TELEPHONE TEANUFACTURING COIWPANY, OF ROCHESTER, NEW YORK, Ii. CUR- IPORATIOIN' OF NEW YORK METERING SYSTEM Application filed. September 4, 1925. Serial N'o.-54,573.

In such'tel-ephone systems it is frequently desirable to provide means'for charging for all 'callsofa certain character originating on certaln of said telephone l1nes. It has been proposed 1n former telephone systems to provide means for automatically charging calls v energization of the hne relay 5 closes a ciras soon as they have beencompleted by the response of the called parties. -Such systems, however, have not fully met practical requirements, because they have failed to provide certain very necessary means for thecharging of calls toofiicial lines such as Trouble or Information calls. Such systems have also failed to provide means to prevent thecharging of a call when the operator disregards a busy signal and connects. a calling telephone line to a line already .in' use. Such systems have further failed to meter calls properly in the case of recalls when a subscriber abandons one connection before its completion and then immediately initiates a second connection. Another failure in previous systems has been that they fail to prevent the operation of the meter when a flash-back busy signal is transmitted from. a distant office i in the case of an inter-office call. It 1s the purpose of the present 1nvent1on to provide metering means which overcome the failures mentioned in previous telephone systems. I

Other features of the invention will appear from the detailed description and the appended claims. A

The drawing diagrammatically represents a portion of a manual telephone system in which a calling telephone lineis' shown at the left. In the center of the. figure there isshown an operators cord circuit, representative of several cord circuits, together with certain equipment common to all the cord circuits at anoperators position. At the right of the drawing there is shown a called telephone line.

It is believed that the invention will best calling substation such as A to the substation of a wanted telephone line such as B. When the subscriber at. A initiates a call by re'-- moving his receiver from its switch-hook, the

line relay 5 is energizedin the well known i.

manner in a circuit extending from grounded'battery through the back contactsof the cut-off-relay' 6 and the two sides of the subscribers line inseries, to ground. The

ing, through the ring contacts of the plug 13 and jack J over the two sides in series of the calling line, tip contacts of the jack J and plug P and thence to ground through the upper winding of relay 8. At the same time the sleeve relay 9 is operated from grounded battery through the sleeve contacts of the plug P and jack J windingof the cut-0E relay 6 to ground. These relays are energized in this circuit and the cut-off relay disconnects the line relay 5 from the control of its telephone line to extinguish the line lamp 7. The sleeve relay 9 onoperating closes a locking circuit for itself through its lefthandlow resistancewinding, its left-hand armature and front contact and thence to ground through the winding of the cut-off sleeve relay 9 is such that in the event that an operator either at the position in question or at another position inserts the answering jack of a second cord circuitinto a multiple jack of this line, the high resistance winding of the sleeve relay at the second cord circuit will not be energized in multiple with the low resistance winding 9 atthe first cord circuit. This arrangement is known as the operators bar feature. 1 7

Also when the sleeve relay 9 is operated it closesa circuit which controls the connection of the operators telephone set to the cord circuit selected for use. This circuit extends from ground, outer armature and .Will not operate in series therewith.

front contact of the relay 9, uppermost armature and back contact of relay 10, winding of the slow releasing relay 11, windings of the relays 12, 13 and 14 in series to grounded battery. The resistances of the relays 13 and 14 are such that the relays 12 and 11 The relay 14, however, is energized in this mentioned circuit and attracts itsarmature to close a circuit through the right-hand winding of the relay 13 for operating this last named relay. The operation of the relay 13 closes a circuit from grounded battery, front contact and armature of the relay 13, lefthand winding of this relay and thence through thewindings of relays 12 and-1l over the remainder of the circuit previously described; The relays 11 and 12 are thus operated and the operation of the relay 11 causes the energization of the slow releasing relay 15 which is effective to connect the operators telephone set to the cord circuit taken for use. Theoperating circuit of the relay 15 is traceable from grounded battery, winding of this relay, front contact and armature of the relay 1]., winding of the relay 16, to ground. In order to indicate that the operators telephone set is connected to a particular circuit, the answering supervisory lamp 17 thereof is dimly lighted in a circuit extendin from grounded battery through the lamp 17, inner armature and front contact of the supervisory relay 8, outer armature and back contact of relay 18, armature and front contact of relay 11 through the winding of relay 16 to ground in multiple with the operating circuit of the relay 15. The resistance of the relay 16 is of sufiicient value that the answering supervisory relay 17 is dimly lighted and indicates to the operator to which cord circuit her telephone set is connected. Such an arrangement is,nec essary where an operator answers several calls at about the same time, instead of completing a call before answering a second one.

The relay 16 is energized in this multiple circuit and at its left-hand armature closes a circuit from ground, armature and front contact of relay 12, winding of the peg count or meter magnet 19 to grounded battery, which circuit energizes the meter preparatory to recording the call being completed at this position. At the inner armature and front contact of the relay 16 a short circuit is closed about the relay 12, causing this relay to retract its armature slowly and thereby effect the deenergization of the magnet 19 which in turn completes the registration on the peg-count meter. At this time an impedance 20 is included in a circuit from ground, front contact and armature of relay 16, armature and back contact ofrelay 12 through the impedance 20, armature and front contact of relay 16 and thence in multiple with the operating circuit of the relay 11 previously described. This arrangement of the impedance 20, while it permits the relay 11 to remain operated, is of such value that a relay similar to 11 at a second cord circuit connected to another telephone'line will not be operated. When, however, in the course of completion of the first mentioned call the relay 16 deenergizes and thereby disconnects the impedance 20, the relay similar to 11 at a second cord circuit is operated in the manner already described to ef feet the connection of the operators telephone set to the second cord circuit. The values of impedance 20, and relays 13 and 14 are such that if an operator partially completes more than two calls simultaneously, all calls are prevented from being completed, thus insuring that the operator will not attempt to answer more than two connections at the same time.

As soon as the relay 15 has extended the operators telephone set to the cord circuit connected to the calling telephone line, the operator inquires from the calling party thereon the number of the wanted telephone line, and then after the usual testing by touching the tip'of the calling plug P to the sleeve of jack J of the wanted telephone line, inserts this plug into jack J. If the wanted line is a party line the operator proceeds to select the proper ringing current to signal the wanted substation thereon. This is accomplished by depressing some one of the common ringing keys 21, 22, 23 and 24 which are common to all the cord circuits at an operators position. Let it be assumed that the ringing key 21 controls the selection of the proper ringing current for signaling the wanted substation B. On the depression of the key 21 by the operator the slow releasing relay 25 is energized.

t the time when the plug P is inserted into the jack J the sleeve relay 26 is energized from grounded battery back contact and continuity spring of relay 10, through the sleeve contacts of plug P and jack J, winding of the cut-oif relay 27 to ground. The relays 26 and 27 are energized in this circuit and the relay 27 disconnects the line relay 28 from the control of its telephone line. The energization of the relay 26 associates the ringing circuit selecting relays 29 and 30 with the relays 25, 31, 82, 33 and 34 controlled by the ringing keys 21 to 24 and with the nonring key 35 which is used when the calling end of the cord circuit is connected to a trunk circuit. with the relays 25 and 26 operated, a circuit is closed from ground, inner front contact and armature of relay 25, inner armature and front contact of relay 26, winding of the relay 30 to grounded battery. Relay 30 when operated closes a locking circuit for itself from grounded battery, its right-hand front contact and armature, back contact and armature of relay 36, right-hand front con- .middle armature and back contact of relay 18, conees- 2 tact and armature of relay 2 6 to ground. At

-for itself from grounded battery through its lower winding, conductor 88, winding of marginal relay 39, armature and continuity spring of relay 10 through the sleeve contacts of the plug P and ack J, winding of the cutoff relay 27 to ground.

The relay 39 at its right-hand armature and front contact closes an energizing circuit for the slow releasing circuit 40, which functions to control the operation of the meter at the calling line in the manner to be described. The operation of the relay 10 opens the energizing circuit of the slow-releasing relay 26, but before this last-named relay deenergizes the holding ground for the various circuits is applied through the innermost lower front contact armature of the relay 10. At the same time that the relays 10 and 30 are operated the ringing relay 41 is energized from grounded battery, resistance, winding of this relay, inner right-hand front contact and armature of the relay 26, out-er armature and front contact of relay 25 to ground. The ringing relay 41 also closes a locking circuit for itself through its front contact and armature, innermost right-hand ductor 42, through the back contact and armature of supervisory relay 36 and thence to ground either at the front contact and armature of relay 26 or the armature and front contact of relay 10. Also at this same time the relay is energized to extinguish the calling supervisory lamp 44 which is lighted as soon as the calling plug P is inserted into the jack of the called line. The operation ofthe t relay 45 opens the lighting circuit of this supervisory lamp as soon as the ringing current is selected, thus providing the feature known in the art as The dark key shelf.

. The operating circuit for the relay 45 extends from grounded battery, its winding, outermost front contact and armature'of relay 26, conductor 37, through the armature and back contact of relay 34, outer armature and front contact of relay 25 to ground. Relay 45 also closes a locking circuit for itself through its right-hand armature and front contact, ar: mature and back contact to relay 18 and thence to ground over the holding conductor 42.

With the ringing selection relay 3O operated, ringing current from the fifty-cycle source, is applied to the bell at the wanted substation in a circuit including conductor 46, inner front contact and armature of the rei lay 30, back contact and armature of the relay 29, winding of the ringing trip relay47,

innermost front contact and armature of the ringing relay41, ring contacts of the plug P and jack J, through the bell of the wanted substation which is that indicated at B, over the upper side of the called line through the tip contacts of the jack J and plug P, armature and front contacts of relay 41 to ground.

Interrupted ringing current is applied over thls circuit n the well known manner until theparty at substationB answers by removing his receiver from its switch-hook, at which time the ringing trip relay47 is instantly operated and at its front contact and armature completes a short circuit about the ringing relay 41 which immediately deenergizes and disconnects the ringing current from the wanted line. Likewise the response of the called party effects the energization of the callingsupervisory relay 36, which relay at its armature and back contact disconnects the holding ground which has been holding the various relayslocked in an operated condition. 1 It will be understood that during the application of the ringing current to the called line a revertive ringing tone or ringing echo is applled to the calling line from the source of ringing tone current through the condenser 49, lowermost armature and front contact of relay 41, right-hand winding of relay 80,1efthand back contact and armature of relay 15,

and over the answering end of the cord circuit" and through the substation circuit of the calling line over the lower side of the cord circuit and thence to grounded battery.

As soon as the called party answers, the calling party is then charged with the call by the operation of the calling line meter which is controlled as follows: The response of the called party actuates the callin supervisory relay 36 which effects the energization of the slow-releasing relay 50 from grounded bat-' tery winding of this relay, front contact and armature of the relay 40, conductor 51, lefthand front contact and armature of relay 36, inner armature and front contact of relay 10 to ground. The operation of the relay 50, in'

turn,"closes the metering circuit from the ing of the position meter magnet 52, back contact andarmature of the relay 40, which deenergizes as soon as the supervisory relay 36 is actuated, middle back contact and armature of the relay 18, armature and front contact of relay 50, sleeve contacts of the plug -P and jack J, conductor 53,'and thence to the line meter magnet (not shown). It will be seen that relay 40 deenergizes due to the fact that relay 89, which controls it, is short-circuited at this time by the circuit completed from grounded battery,- lower winding of relay 10, right-hand front contactand armature of relay 36, armature and continuity spring of relay 10, and thence to ground L3 terrupt the metering circuit just described and thereby register the call on the calling line meter.

At the termination of the conversation the calling-subscriber A replaces his receiver on its switch-hook, which opens'the circuit of the supervisory relay 8 and thereby completes a circuit for lighting the supervisory lamp 17 from grounded battery, lower armature and back contact of relay 8, inner arma ture and front contact of relay 9 to ground. Also when the called party at substation B replaces his receiver on its switch-hook, the calling supervisory relay 36 deenergizes and the calling supervisory lamp a4 is lighted from grounded battery, left-hand back contact and armature of relay as, c nductor 1-2, lefthand back contact and armature of relay 36, armature and front contact of relay 10 to ground. The lighting of the lamps 17 and 14; is a signal to theoperator to remove the plugs P and P from th jar; with which they have been in engagement.

In the event that the subscriber at substation A desires to initiate a recall, he does so by temporarily opening the contacts of the hook-switch at his substation. This is effective to open momentarily the energizing circuit of the supervisory relay 8, which re tracts its armature and thereby closes a circuit for the recall relay 18 extending from grounded battery, resistance, winding of this relay, lower back contact and armature of relay 8, conductor 54, upper front contact and armature of relay 10, which is now energized due to the fact that the plug P is still in engagement with the jack of the line last called, conductor 55, front contact and armature of relay 9 to ground. Relay 18 on operating closes a locking circuit through its innermost front contact and armature and thence over conductor 54 and the remainder of the circuit previously described. This last circuit is independent of the control of the relay 8. l/Vhen the subscriber again closes the hook-switch contacts the relay 8 remains operated. The answering supervisory lamp is now intermittently lighted in a circuit completed from grounded battery through the lamp 17, inner armature and front contact of relay 8, outer armature and front contact of relay 18, winding of the relay 56 through the interrupter 57 to ground. The intermittent lighting of the supervisory lamp 17 is a signal to the operator that a recall has been initiated, and she thereupon removes'the plug P from'the jack J and ascertains the number that the calling subscriber now desires. The calling party should be charged for the original call and for the recall.

For this reason, the metering circuit extending through the back contact and armature of relay 40 is opened at the righthand back contact and middle armature of the relay 18.

If the original call has been completed at the time when the calling subscriber initiates the recall, the original call is charged on the calling line meter in the usual manner, and the operator removes the plug P from the jack of the called line, after which a second line may be selected and signalled in the manner already described. This recall as in the case of the original call is charged on the meter of the calling line.

If, however, the calling subscriber abandons the original call and initiates a recall before the called party has ansWered,-the calling supervisory relay 36, in the cord circuit of the original call, is not operated, with the result that this slow releasing relay 50, at the left of the diagram is not operated to close a break-point in theoperating circuit of the calling line meter magnet. The recall, however, is charged to the calling line, if the called party responds, under which conditions the operation of the calling line meter takes place in the manner already described. Of course, if the recall is abandoned before the called supervisory relay 36 is operated, no charge is recorded on the calling line meter, since relay 39 is short-circuited at relay 18.

If the calling subscriber initiates a call to a distant substation, which is completed over a trunk circuit such as 61, the response of the called subscriber effects the energization of the supervisory relay 36, after which the meter is controlled over the cord circuit inthe manner already described. It should be noted that a resistance of relatively low value, is included in the sleeve conductor of trunk 61. This resistance is such that the marginal relay 39 will energize in series therewith. If the calling subscriber initiates a call to an oflicial line, such as Trouble, Information, etc., the cord circuit is so arranged, that the calling subscriber is not charged for such a call; Such an official trunk line is indicated at 71 and the sleeve conductor associated therewith, includes a relatively high resistance 72. This resistance is of such high value, that the marginal relay 89, which is arranged to be connected in series therewith through the sleeve contact of the plug P and the sleeve conductor of the trunk 71, is not operated, with the result that the slow releasing relay 40, whose operating circuit is contrcllcd at the armature and front contact of relay 39 is not energized. Therefore, relay 50 is not operated at this time so that the metering circuit previously described is not completed and the call is not charged.

In the event that the operator disregards the busy signal when she tests the called line by touching the tip of the plug P to the sleeve of the jack J means are provided to prevent the operation-of-the calling line meter to charge for the connection. In case ofsuch a connectiomthe call proceeds in a normal manner up to the time when the operators telephone set is connected to the calling line.

hen, however, the plug P is inserted into the jack such as J of the busy called line,

- the marginal sleeve relay 26, which is norsleeve relay 26 does not receive sufiicient current to energize it. Under the normal operation of the system, as soon as the calling plug is in a jack of the called line, the calling supervisory relay dais-lighted from grounded battery through the lamp,- back contact and armature of relay 45, conductor 42, back contact and armature of relay 36, front contact and armature of relay26,:to ground. The

lighting of this lamp is anindication to the operator that the calledparty is being signalled. lVhen, however, the operator mistakenly makes connection to a busy line, the failure of relay 26 to operate, prevents the lighting of the lamp 44. Also since relay 26 is not operated, the ringing control keys 21 to 24 inclusive and key 35, are not operatively connected to the cord circuit taken for use, so that asubscriber on theselected busy line cannot the operators telephOne set with the cordcircuit in use, is controlled by the slow-releasing relay 11. This last named relay is controlled at the upper, back contact and armature of relay 10 and at the front contact and armature of relay 9, to ground. 7 Since the original energizing circuit of the relay 1O is controlled at a front contact and armature of relay 26, relay 10 cannot be operated to open the circuit of the relay 11. As soon as the operator 'removes the plug P from the jack of the calling line, the relay 9 will deenergize, efiecting in turn the deenergization of relays 11 and 15 to restore the operators telephone set to common use.

If the operator connects her cord circuit to a trunk circuit, such as 61, over which a busy flash back signal is transmitted, such a call -is likewise not charged on the calling line meter.

,As is well-known, such flash back signals intermittently open the operating circuit of the calling supervisory relay such as 36 which circuit includes the tip and ring conductors of the selected trunk. It is desirable in case of connections where a flash back busy signal is applied not to charge the con nection on the meter of the calling line. In the case of such connection the relays39 and 40 are energized in the manner already described and on'the first energization of the calling supervisory relay 86, the slow-releasing relay is energized. This last named relay is so designed that it holds its armature attracted during the intermittent oper ation of the supervisory relay, which conrols the operating circuit. The metering circuit is held open at this time at the left-hand back contact and armature of relayjlO. This con dition exists until the calling subscriberterininates the call in response to the busy signal; lVhen the calling subscriber replaces his receiver on its switch-hook, the flash recall relay. 18 is operated in the manner already described and at its middle armature holds open themetering circuit until the operator re-' movesthe plugs P and P from the jacks with which they have been in engagement.

It will thus be seen that a manual telephone system has been provided which evercomes thedifiiculties encountered in automat-- called telephone lines or official lines, auto-' matically registering the calls completed to the telephone lines, and automatically preventing the chargingof calls extended'to oflicial lines. r

2. In a telephone system, a plurality of telephone 1ines,-certain of which are party lines, ,meansincluding a plurality of cord circuits for interconnecting said telephone lines, a registerv for each of certain of said lines, sources of ringing current of different characteristics for selectively signaling said party lines, a single key for each source of ringing current, said ringing keys being common to said cord circuits, means for associating said ringing keys with a'cord circuit taken for use, and means controlled by the completion of a call from a' telephone line provided with a register to another telephone linea'nd the response of the signalled party circuits, means for associating said ringing keys with a cord circuit taken for use, and means responsive to the completion of a call from a telephone line provided with a register, to a called telephone line and the response of the signalled party thereon for operating said last mentioned register.

4:. In a telephone system, a plurality or" telephone lines, certain of which are party lines and others are official lines, means including a plurality of cord circuits for interconnecting said telephone lines, a register for certain of said lines, sources of ringing current of different characteristics for selectively signalling said party lines, a single key for each source of ringing current, said keys being common to said cord circuits, means for associating said ringing keys with a cord circuit taken for use, and means responsive to the extension of a calling telephone line provided with a register to another telephone line for operating said register, said means being responsive to the completion of a call from said calling telephone line to-an official line for preventing said last mentioned register from operating.

' 5. In a telephone system, a plurality of telephone lines, certain of said telephone lines being party lines, means including a plurality of cord circuits for interconnecting said telphone lines, a register for each telephone line of a certain group, means responsive to the completion of a connection from a telephone line of said group to another telephone line for operating the register of the calling telephone line, a signal at each cord circuit, and means responsive to the initia tion of a recall by a telephone line for intermittently actuating said signal.

6. In a telephone system, a telephone line provided with a message-charging device, a plurality of other telephone lines, means ineluding a cord circuit for interconnecting said first mentioned telephone line with any of said other telephone lines, an official telephone line, an operating circuit for said message-charging device, and discriminating means including a relay controlled in one manner over a telephone line and said cord circuit and in another manner over said olficial line and said cord circuit, said discrimisaid other telephone lines, an oiiicial telephone line, an operating circuit for said message-charging device, and discriminating means including a marginal relay controlled in one manner over a telephone line and said cord circuit and in another manner over said ofiicial line and said cord circuit, said discriminating means functioning to control the closure of said operating circuit.

.8. In a telephone system, a calling tele phone line provided with a sleeve conductor and with a message-charging device, an oilficial telephone line provided with a sleeve conductor having a high resistance therein, a plurality of other telephone lines each provided with asleeve conductor having a low resistance therein, a cord circuit for interconnecting a calling telephone line with said ofiicial line with any of said other telephone lines, said cord circuit being provided With a sleeve conductor, a circuit for said message-charging device including a sleeve conductor ofsaid calling telephone line and the sleeve'conductor of said cord circuit, discriminating means including a marginal relay associated with said cord circuit, and a circuit for said marginal relay completed through the sleeve conductor of the official line and through the sleeve conductor of one of said other telephone lines when the cord circuit is connected thereto, sald circult for the message-charging device being placed in its operating or non-operating condition by said marginal relay.

9. In a telephone system, calling telephone lines provided with message-charging devices, party lines each provided with substations, means including a plurality of cord circuits for interconnecting calling telephone lines with any wanted party line, each cord circuit being provided with sleeve conductors, a plurality of sources of current of different characteristics for selectively sig naling stations on party lines, a single ringing key common to said cord circuits provided for each source of ringing current, a sleeve relay for each cord circuit operated through one of the sleeve conductors of its cord circuit and the sleeve conductor of a connected party line, said sleeve relay functioning to connect said common ringing key to its cord circuit for controlling the selection of ringing current of the proper characteristic to signal the wanted station on said party line, a marginal relay at said last mentioned cord circuit, means including said sleeve relay for controlling the operation of said marginal relay, a circuit for the message-charging device of the calling telephone line connected to said cord circuit, and

means including said marginal relay for controlling the completion of said last mentioned circuit.

10. In a telephone system, a calling telephoneline provided with a message-charging device, wanted telephone lines, means including a cord circuit for interconnecting :said calling telephone line with any of said signal, said recall relayhaving a circuit controlled at a back contact of said supervisory relay and contacts of the sleeve relay and said calling relay of sald cord circuit, a

locking circuit for said recall relay independ-i ent of said supervisory relay, and an operating circuit for said message-charging device having atleast one break-point controlled at said recall relay.

11. In a telephone system, a calling tele-- phone line provided with amessage-charging device, wanted telephone lines provided with sleeve conductors, means including cord circuits for interconnecting said telephone lines, a marginal sleeve relay for the calling end of each cord circuit arranged to be controlled over the sleeve conductor of a wanted telephone line when its cord circuit is connected thereto, said marginal relay being designed not to operate when connected in multiple with a second slmllar sleeve relay'at a second cord circuit already connected to said wanted telephone line, an operating circuit tor said message-charging device, and means including the marginalrelay of said first mentioned cord circult for controlling the completion of sa1d operatlng circuit.

12; In a telephone system, a plurality of telephone lines, each provided with a messagecharging device, a plurality of wanted telephone lines, means including a plurality of cord circuits for interconnecting calling telephone lines with wanted telephone lines, an operators telephone set common to said cord circuits, means operating responsive to the connectionot cord circuit to one of said calling telephone lines for connecting said operators telephone set to said cord circuit to the exclusion of other cord circuits, means for indicating to which cord circuit an operators telephone set is connected, and means controlled by the connection of said last mentioned cord circuit to a telephone line and the response of the aarty thereon for automatically operating the message-charging device of said calling telephone line.

13. In a telephone system, a plurality of telephone lines, each provided with a message-charging device," a plurality of party lines, means including a plurality of cord circuits for interconnecting calling telephone lines with party lines, an operators telephone set common to said cord circuits, means ope 'ating responsive to the connection of a cord c1rcu1t to one of sald calling telephone lines for connecting said operators telephone set to said cord c1rcu1t to the exclusion of other cord circuits, means for indicating to which cord circuit an operators telephone set is connected, a plurality of sources'of ringing current of different characteristics to signal said party lines selectively, a single ringing key for each source of ringing current common to said cord circuits, means torconnectlng sa1d common ringing keys to the cord circuit to which said operators telephone set is connected, and means controlled by the connection of said last mentioned cord circuit to a party line and the response of the party thereon set to said cord circuit to the exclusion of other cord circuits, means for indicating to which cord circuit an operators telephone set is connected, a plurality of sources of ringing current of different characteristics to signal the stations on said party lines selectively, a single ringing key for each source of ringing current common to said cord circuits, means for connecting said common ringing keys to the cord circuit to which said opera-tors telephone set is connected, a recall signal, a recall relay controllin said signal, said recall relay having a circuit controlled in part by said supervisory relay, and an operating circuit for said message-charging device of said last mentioned calling telephone line controlled at one polnt by said recall relay.

signaling the wanted substation on a party line, a single key tor each source of rlnging current, said ringing keys beingicommon to a plurality of cord circuits, a sleeve relay for each cord circuit having an operating circuit completed'ov'er the sleeve conductor of gnu the line with which its cord circuit is connected, a second relay, an initial energizing circuit for said second relay controlled at contacts of said sleeve relay and controlled by one of said common ringing keys, a substitute circuit for said second relay including said last mentioned sleeve conductor, a marginal relay included in said substitute circuit in series with said second relay, an operating circuit for the message-charging device of the calling line connected with said last mentioned cord circuit, said operating circuit having a break-point therein, a third relay controlling said break-point, and a circuit for said third relay controlled by said marginal relay.

16. In a telephone system, a plurality of calling telephone lines each provided with a message-charging device, a plurality of part-y lines each provided with a plurality of substations, a sleeve conductor for each party line having a relatively small resistance therein, an oficial line provided with a sleeve conductor having a relatively high resistance therein, means including plurality of cord circuits for interconnecting said calling telephone lines with party lines and with said official line, supervisory means for each cord circuit, a plurality of sources of ringing current of different characteristics for selectively signaling the wanted substations on the party line, a single key for each source of ringing current, said ringing keys being common to a plurality of cord circuits, a sleeve relay for each cord circuit having an operating circuit completed over the sleeve conductor of the line with which its cord circuit is connected, a sec- 0nd relay, an initial energizing circuit for said second relay cont-rolled at contacts of said sleeve relay and controlled by one of said common ringing keys, a substitute circuit for said second relay, a marginal relay included in series with said second relay, a third relay having a circuit controlled by said marginal relay, a fourth relay governed by the operation of said supervisory means of said last mentioned cord circuit, and an operating circuit for the message-charging device of the calling line connected to said cord circuit, said operating circuit being controlled at contacts of said third and fourth relays.

17. In a telephone system, a plurality of calling telephone lines each provided with a message-charging device, a plurality of party lines each provided with a plurality of substations thereon, a sleeve conductor for each party line having a relatively small resistance therein, an oflicial-line provided with a sleeve conductor having relatively high resistance therein, means including a plurality of cord circuits for interconnecting said calling telephone lines with party lines and with said ofiicial lines, a plurality of sources of ringing current of different characteristics for selectively signaling the sleeve relay and controlled by one of said 3 common ringing keys, a substitute circuit for said second relay includlng said last mentioned sleeve conductor, a marginal relay 1ncluded in series in the substitute circuit of said second relay, an operating circuit for the message-charging device of the calling line associated with said mentioned cord circuit, said operating circuit having a breakpoint therein, a third relay controlling said break-point, a circuit for said third relay controlled by said marginal relay, a supervisory relay having an operating circuit including the two sides of the calling line and the answering end of said cord circuit in series, G

a recall signal, a recall relay controlliru said recall signal, said recall relay having a circuit initially controlled at a back contact of said supervisory relay, and means controlled by said recall relay for disabling said marginal relay.

18. In a telephone system, a plurality of telephone lines each provided with answering jacks and a message-charging device, two

groups of cord circuits, an operators telephone set for each group of cord circuits, means including an operators bar relay of the cord circuit connected to a calling telephone line for connecting an operators telephone set to said cord circuit to the exclusion of other cord circuits, said operators bar relay having a high resistance winding and a low resistance winding, a sleeve conductor for each cord circuit normally connected in series with the high resistance winding of said operators bar relay, the low resistance Winding of said operators bar relay being connected in series with said sleeve conductor on the energization of said relay whereby a second operators bar relay connected in multiple therewith is not operated, and an operating circuit for said message-charging device including said last mentioned sleeve conductor.

19. In a telephone system, a calling telephone line provided with a message-charging device, a plurality of telephone lines, an official line, a cord circuit for connecting said calling telephone line to any of said lines, a calling supervisory relay for said cord circuit actuated by the response of a party on any of said called lines to which its cord circuit is connected, a second relay controlled in one manner by the connection of the cord circuit to one of said telephone lines and in another manner in the response to the connection of said cord circuit to said oflicial line, an operating circuit for said message-charging device controlled by said second relay, and means including said calling supervisory relay for disabling said second relay.

20. In a telephone system, a calling telephone line provided with a message-charging device, a plurality of telephone lines, an official line, a cord circuit for connecting said calling telephone line to any of said lines, a calling supervisory relay for said cord circuit actuated by the response of a party on any of said called lines to which its cord circuit is connected, a second relay controlled in one manner by the connection of the cord circuit to one of said telephone lines and in another manner in response to the connection of said cord circuit to saidoflicial line, a slow releasing relay actuated in response to the operation of said calling supervisory relay, an operating circuit for said message-charging device controlled by said second relay and by said slow releasing relay, and means including said calling supervisory relay for disabling said second relay.

21. In a telephone exchange system, a calling subscribers line, a first called subscribers line having a certain resistance sleeve circuit, a second called subscribers line having a certain other resistance sleeve circuit, a link circuit for interconnecting said calling line and either of said called lines, a supervisory relay in said link circuit operating when the called subscriber answers, a position meter associated with said link circuit, a marginal relay controlled over the sleeve of said link circuit and adapted to be operated when said link circuit is connected with one of said called lines and not with the other, and means jointly controlled by said supervisory relay and said marginal relay for operating said meter.

22. In a telephone exchange system, a calling subscribers line, a first called subscribers line having a certain electrical condition, a second called subscribers line having a difierent electrical. condition, a link circuit for interconnecting said calling line and either of said called lines, a supervisory relay in said link circuit adapted to be operated when a called subscriber answers, a position meter associated with said link circuit, a marginal relay controlled over said link circuit and adapted to be operated when said link circuit is connected to one of said called lines but not to the other, and means jointly controlled by said supervisory relay and said marginal relay for operating said meter.

23. In a telephone exchange system, a calling subscribers line, a first called subscribers line having a certain resistance sleeve circuit, a second called subscribers line having a certain other resistance sleeve circuit, a link circuit for interconnecting said calling line and either of said called lines, a supervisory relay in said link circuit operating when the called subscriber answers, a meter, a marginal relay controlled over the sleeve of said link circuit and adapted to be operated when said link circuit is connected with one of said called lines and not with the other, and means jointly controlled by said supervisory relay and said marginal relay for operating said meter.

24. In a telephone exchange system, a call ing subscribers line, a first called subscribers llne having a certain electrical condltion, a second called subscribers line having a different electrical condition, a link circuit for JOHN H. LEVIS, JR. 

